1. Field of the Invention
The present invention relates to a device under test (DUT) board and a testing method using the DUT board, in particular, a DUT board and a testing method using the DUT board applied to a high-speed LSI.
2. Discussion of Background
Along with a high speed, a large capacity and expansive functions of LSI, the trend of packaging is in a transition to a ball grid array (BGA). A device for testing is also developing into one applicable to an increased number of pins and various testing modes in conformity with a function of LSI and with a package.
FIG. 18 illustrates a structure of a conventional testing device. In FIG. 18, numerical reference 1000 designates a device for testing (hereinafter referred to as a tester) constructed by a tester body 1004 and a test head 1006. The tester body 1004 includes a timing generator 1001 for generating a necessary timing signal as a condition for testing, a waveform formatter 1002 determining a waveform of rise and fall timing, and a unit for measuring a power source and a DC 1003 having a power source for driving a device, a DC measuring unit of the device and so on.
Further, the test head 1006 transfers a signal between an LSI under test 1005 based on a control signal obtained form the tester body 1004 through a cable 1018.
When the LSI under test 1005 is tested, a test signal is generated from a tester driver 1008 of a pin electronics 1007 accommodated in the test head 1006. The test signal is applied to the LSI under test 1005 through a POGO pin 1009, a wire 1011 of a DUT board 1010, a socket 1012, an electrode 1013 of the socket, a package 1014 and a wire 1015 of the package 1014.
Further, a reaction signal from the LSI under test 1005 is transmitted to a tester comparator 1016 of the pin electronics 1007 through a similar path to that described above. Based on a comparation with an expected value 1017 conducted in the tester comparator 1016, it is judged whether or not the LSI under test 1005 operates as designed in the tester body 1004, wherein the tester body 1004 receives a result of the comparation from the test head 1006.
FIG. 19a is a cross-sectional view of a part of a conventional socket when a package is installed in the conventional socket. The socket 1012 has a contactor 2014 for electrically connecting with the package 1014 and the DUT board 1010. FIG. 19b is an enlarged cross-sectional view of a portion 2000 in FIG. 19a, in which a solder ball 2011 is interposed in the contactor 2014.
However, in the conventional socket, the conventional DUT board, and the testing method using these, an influence of a power source and a ground bounce becomes conspicuous by an inductance L when an operation of the LSI under test 1005 is operated at a higher speed and in a lower voltage, whereby the LSI under test 1005 is efficiently operated.
Specifically, the inductance L of an electrode of the socket is 20 nH per a line. Therefore, provided that the LSI under test 1005 is operated at 1000 Mz, a gate count is 1M gates, an operating ratio of the gate is 40%, a switching time is 300 ps, and the number of electrodes of a power source is 200, a bounce on the ground side has characteristics that a consumption current of 1 MGxc3x970.4 xc3x9710 uA=4A and a back voltage of 20 nH/200 pinxc3x974A/300 ps=1.3V.
Similarly, the power source of the device suffers from a similar problem. Provided that the power source is 2.5V, the voltage becomes 1.2V with a drop of the voltage of 1.3V, whereby the operation becomes deficient. Therefore, it is necessary to reduce the inductance per a pin. If the bounce is planned to restrict within 5% of the voltage of the power source, it is 2.5Vxc3x970.05=0.125V.
In case of the above example, because 1.3V occurs at 20 nH, 0.125V leads 1.92 nH. In other words, in case of the contactor of the ordinarily used socket, a length of 1 mm corresponds to about 1 nH, the length of the electrode should be about 2 mm. Accordingly, there is a problem that a function test for verifying a logic becomes defective in use of the conventional socket and the conventional DUT board.
According to a first aspect of the present invention, there is provided a DUT board electrically connected with electrodes of a package for testing comprising contactors, on which the electrodes of the package are mounted to be directly attached to the contactors.
According to a second aspect of the present invention, there is provided the DUT board according to the first aspect of the invention, wherein the contactors are a strip-like metallic plate having spring elasticity, in which a longitudinal notch is formed at a center.
According to a third aspect of the present invention, there is provided the DUT board according to the first aspect of the invention, wherein the contactor is a metallic plate having spring elasticity in which a notch in a U-like shape is provided and a part of the metallic plate is obliquely bent while maintaining a part of the metallic plate plan along the notch.
According to a fourth aspect of the present invention, there is provided the DUT board according to the third aspect of the invention, wherein the contactor is obliquely bent so as to be partly curved along a notch.
According to a fifth aspect of the present invention, there is provided the DUT board, wherein the contactor is bent while maintaining a part of the contactor plane.
According to a sixth aspect of the present invention, there is provided the DUT board according to the third aspect of the invention, wherein the contactor is obliquely bent, and in the bent portion, parallel lines or grid-lines are formed on a surface of the contactor along a notch.
According to a seventh aspect of the present invention, there is provided the DUT board, wherein the contactor is obliquely bent, and in the bent portion, a dot-like protrusion is provided on a surface thereof along a notch.
According to an eighth aspect of the present invention, there is provided the DUT board according to the first aspect of the invention, wherein the contactor is bent in a V-like shape.
According to a ninth aspect of the present invention, there is provided the DUT board according to the first aspect of the invention, a pattern is formed on a principle surface of the contactor.
According to a tenth aspect of the present invention, there is provided the DUT board according to the second aspect of the invention, further comprising a slide for opening and closing the contactor.
According to an eleventh aspect of the present invention, there is provided the DUT board according to the third through the eighth aspects of the invention, further comprising a guiding mechanism for constantly maintaining a position of the electrodes of the package, and a pushing mechanism for pressing the electrodes of the package and the contactors.
According to a twelfth aspect of the present invention, there is provided the DUT board according to the ninth aspects of the invention, further comprising a guiding mechanism for constantly maintaining a position of the electrodes of the package, a pushing mechanism for pressing the electrodes of the package and the contactors, and a conductive rubber provided between the electrodes of the package and the contactors.
According to a thirteenth aspect of the present invention, there is provided the DUT board according to the tenth through the twelfth aspects of the invention, further comprising a structure of separating and securing.
According to a fourteenth aspect of the present invention, there is provided a testing method using the DUT board according to the tenth and twelfth aspects of the invention, wherein the electrodes of the package and the contactors are freely connected and disconnected, and an inductance is reduced.
According to a fifteenth aspect of the present invention, there is provided a testing method using the DUT board according to the thirteenth aspect of the invention, wherein the DUT board is freely connected and disconnected, and an inductance is reduced.